Hitherto, a wide variety of cephalosporin type antimicrobial agents have been disclosed in a number of publications. Of these known compounds, cephalosporin compounds having 2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido group at the 7-position and a substituted pyridiniomethyl group at the 3-position of the cephem ring have recently been disclosed, for example, in Japanese Patent Application (OPI) No. 192394/82 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"). A typical example of this type compound described in the above prior art is 7.beta.-[2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-[4-(pyridin-2- yl)-1-pyridinio]methyl-3-cephem-4-carboxylate. However, this known compound is still unsatisfactory as antimicrobial agent.